Electric lamp with current bridge



Jan. 12, 1954 5 Cj ELECTRIC LAMP WITH CURRENT BRIDGE Filed June 5, 1951 Patented Jan. 12, 1954 UNITED STATES PATENT OFFICE ELECTRIC LAMP WITH CURRENT BRIDGE Selfrid Gunnar fihlund, Enskede, Sweden Application J 11110 5, 1951, Serial No. 229,887 Claims priority, application Sweden June 5, 1950 3 Claims. (01. 315-75) This invention relates to an electric lamp with a current bridge consisting of a metal strip covered with a thin insulating layer.

Such current bridges are known in a general Way and they usually consist of an oxidized metal strip, for instance of aluminum strips oxidized by electrolytic treatment. The insulating layer must, however, not necessarily consist of oxides, but some other covering, such as sulphides, can also be employed.

In the known design of such lamps, the metal strip provided with an insulating layer is usually bent over the feeders of the lamp. When bending the strip, there is, however, often a risk of damaging the insulating layer so that a large percentage of rejects sometimes must be expected in the manufacture of such lamps.

Accordin to this invention, a difierent way of attaching the current bridge is proposed, in such a manner that the strip constituting the current bridge is held clamped between the feeders of the lamp bent towards each other.

In an electric lamp with an incandescent filament carried by a supporting wire, one end of the strip can be welded onto the supporting wire, while the other end of the strip is clamped between the feeders. This ensures that the strips are not dislocated, and at the same time, if the filament is broken, one of the filament halves carried by the supporting wire can still be utilized.

An example of a lamp embodying the invention is shown in the accompanying drawing.

Fig. 1 shows a lamp with a filament mounted in inverted V-shape for, for instance, Christmas tree series illumination, as seen at right angles to the plane through the filament.

Fig. 2 shows the mounting of the filament seen at right angles to the plane of Fig. 1.

The lamp has an envelope 1, in which is arranged a so-called pearl foot ll, through which two feeders 2 and 9 pass, and which carries a supporting wire 3. The supporting wire 3 at its top is provided with an eye 5, through which the top 4 of a spiral filament 6 mounted in inverted V-shape is threaded. The ends of the filament are welded onto the feeders 2 and 9. These feeders are bent towards each other at parts I and I0, and between these bent parts a strip 8 suitable for serving as a current bridge is clamped. The clamping, as will be seen, is point-shaped, and the contact pressure is provided by the springiness resulting from the bending stress originated when the current bridge strip is squeezed between the feeders already bent towards each other. In order to ensure, as already mentioned, that strip 8 is not dislocated and to be able to use spiral length 9-4 and vice versa in the case of a spiral fracture or for instance length 2-4, the bridge strip is attached by welding to supporting wire at part [2.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. An electric lamp comprising a filament, me tallic feed wires to which the ends of said filament are welded, said wires being bent to close proximity to each other at a given place and a body of metal having a thin surface layer of insulating material thereon resiliently clamped between said wires at said given place with substantially point contacts between the plate and the respective wires.

2. A lamp as defined in claim 1 in which said body of metal is in the form of a flat plate.

3. A lamp as defined in claim 1 including a support wire for holding the filament intermediate its ends, said body of metal being welded to said support wire.

SELFRID GUNNAR CiHLUND.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,687,530 Van Horn Oct. 16, 1928 2,482,509 Rively Sept. 20, 1949 FOREIGN PATENTS Number Country Date 605,649 Great Britain July 28, 1948 

